In Tamil Nadu, Anjaneyar Jayanthi is observed on Moolam Nakshatram in the Margazhi month or Margali Masam, which is one of the most auspicious months in Tamil Calendar. In 2018, Hanuman Jayanti in Tamil Month Margazhi is on January 4. Hanuman Jayanthi is observed during various time of year by different Hindu communities. Majority of the people observe it on the Purnima or full moon day in the Chaitra month (March - April).

It is widely believed that Lord Hanuman is present where the story of Lord Ram is recited. Therefore people read the Ramayana on the day or recite prayers dedicated to Rama. The Sundara Kandam chapter of Ramayana is read by most people.

Special prayers are held on the day in Hanuman Temples and are visited by large number of devotees.

At home, idols or pictures of Hanuman are thoroughly cleaned at dawn. Idols and pictures are smeared with Sindhoor. Sweets and bananas are offered to Hanuman.

Some of the popular Anjaneyar Temples in Tamil Nadu organize various rituals. Special prayers and pujas are held on the day. Food donation, feeding of animals and special prasadam are distributed on the day.